Construction struts (they are also called channels and framing channels) are well known and ubiquitous in construction, especially in commercial buildings. One of their purposes is to enable pipes and conduits to be installed by being clamped to the construction struts.
A good reference for construction struts as well as accessories for use with them can be found in the catalogue of ERICO International Corporation of Solon, Ohio, and their website ERICO.com. One of the most commonly used accessories with construction struts are clamps for clamping pipes and conduits to the construction strut. Several of these can be found in the ERICO catalogue including a design that is also described in U.S. Pat. No. 4,429,440 the content of which is incorporated by reference herein.
Another good reference to these products is Thomas&Betts Corporation of Memphis Tenn.
FIG. 1 shows in cross-section a typical construction strut (taken from the catalogue of Thomas & Betts). These are made by the various manufacturers to dimensions which are either the same or sufficiently substantially the same that accessories will fit on those made by the various manufacturers as shown on FIG. 1 but varying in height. Therefore a standard configuration of the top and inturned flanges and width is adopted by the industry which enables the use of various accessories regardless of the manufacturer of the construction strut. There are other standardized features one of which is providing slots on the bottom of the construction strut. Using the slots, some accessories can be attached to both the top and the bottom of the construction strut. A typical accessory is the clamp which is the subject of the present invention.
FIG. 2 shows three common types of pipe clamps of the prior art designated E1, E2 and E3. Pipe clamp E1 features separate sides 20a and 20b which are held in the construction strut 10. A perspective drawing of type E1 is shown in the ERICO catalogue at page 78. Type E1 is installed by fitting the separate sides 20a and 20b into the construction channel with the pipe between them, and then fastening them together with the threaded fastener and nut 22. Type E1 has the disadvantages of having four parts (including the nut), most inconveniently, the clamping sides 20a and 20b being separate. It is difficult to install when there are several pipes to be installed close to each other because a screwdriver cannot be used and they have to be manipulated to be held in position as the screw is inserted to keep them assembled. Notably, often installation of pipes and conduits has to be done in very tight and crowded spaces.
Type E2 in FIG. 2 is made to improve type E1 by allowing easier access to the fastener head but it too has disadvantages; when the fastener is tightened it tends to move to a more vertical position exposing the head and putting uneven pressure on the pipe.
Type E3 is shown in the Erico catalogue on page 80 and it is shown in U.S. Pat. No. 4,429,440. It has the disadvantage that it does not wrap around the pipe so the pipe is not firmly gripped and is subject to twisting. Also, if the fastener is tightened too much the pipe can be crushed; therefore, this type cannot be used on heavy duty work requirements.
All three of these illustrated fasteners has the additional disadvantage that there is a portion exposed allowing injuries to workers who pass under them as shown in FIG. 2 and also injury to hands and arms when trying to work in a crowded space. One of the problems in this work is that it is often done in tight and crowded spaces and with a lot of adjacent pipes and conduits.
There is a need for a clamp that is easy to install, does not expose a fastener head, allows ready access for tightening and has a clamping surface to keep it firmly in place.
Also there is often a need to clamp a pipe or conduit to the opposite bottom side of the construction strut, where there are slots; a versatile clamp that will work on both sides of the construction strut is very desirable Also, there is a need not only for such a versatile clamp, but one that in accomplishing that versatility also is easy to install.
In construction it is often the case that construction struts will be stacked. This is shown in FIG. 2b. In the figure stacked construction struts are shown. For illustrative purposes, in between struts 10 and 10a there are clamps of the type E1, E2 (as in FIG. 2a) and between struts 10 and 10b there are clamps of the type E3 (as in FIG. 2a). The problem with both of these clamp types lies in the dimension N, between the struts. The present invention recognizes the desirability of reducing that distance.